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Oxidative stress has a pivotal role in the pathogenesis of diabetic retinopathy (DR). . (JRL) leaf extract has hypoglycemic and antioxidative properties. This study aimed to determine the ameliorative effects of JRL against diabetic retinopathy. The DR rat model was generated by injection of streptozotocin (STZ). A subset of the diabetic rats received JRL or metformin after the onset of hyperglycemia. Histopathology and immunohistochemistry of apoptotic and inflammatory factors were assessed along with biochemical assessments of lipid peroxidation and antioxidant status. Lipid peroxidation level and catalase activity significantly improved after JRL consumption ( <0. 001). Degeneration of the retina attenuated after JRL consumption. Attenuation of the caspase-3, COX-2, PARP, and S100B expression could be detected significantly ( <0. 001) in the JRL-treated rats. While, blood glucose level decreased after JRL consumption ( <0. 001). JRL leaf extract exert protective effects against diabetic retinopathy.

Juglans regia L. is a good host for Serendipita indica. Under drought condition, seedlings colonized with S. indica showed higher values in plant height, total fresh biomass, root/shoot ratio, relative growth rate, leaf relative water content and chlorophyll content, gas exchange parameters, maximal photochemical efficiency, photochemical quenching, and effective photosystem II quantum yield than the uncolonized seedlings. It suggested beneficial effects of S. indica on host plants’ growth and physiological parameters in response to drought. In comparison with the uncolonized seedlings, S. indica–colonized seedlings showed lower levels in hydrogen peroxide, superoxide anion, malondialdehyde, and relative electrical conductivity under drought condition, suggesting the ability of S. indica to prevent or retard the accumulation of reactive oxygen species and to diminish the oxidative injure. Furthermore, walnut seedlings responded to drought by actively accumulating osmotic regulation substances including soluble protein, soluble sugar, and proline. Root colonization with S. indica was more conductive to the accumulation. Moreover, in response to drought stress, walnut seedlings, regardless of colonization, increased activities of superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase, and glutathione reductase, levels of ascorbate and glutathione, and ratios of reduced ascorbate/dehydroascorbic acid and reduced glutathione/oxidized glutathione in leaves and roots. S. indica colonization induced much more increase in the abovementioned indicators as compared to the uncolonized seedlings. Overall, S. indica colonization alleviated the detrimental effects of drought stress by altering root system, enhancing osmotic adjustment, and repressing the accumulation of reactive oxygen species via stimulating antioxidant system including enzymatic and nonenzymatic components.Key points• S. indica stimulated root growth of walnut seedlings under drought condition.• S. indica accelerated osmotic adjustment under drought condition.• S. indica activated antioxidant defense mechanism under drought condition.

We investigated whether juglone is the only allelochemical in a leaf extract from the walnut (Juglans regia L.). This was achieved through comparisons of the effects of pure juglone (1 mM, 100 μM, 10 μM control juglone) and J. regia leaf extract (prepared as 1 mM, 100 μM leaf juglone) on seed germination, seedling growth, and secondary metabolism of the selected crop vegetables. Two control treatments were also applied, as extraction medium and water. For inhibition of seed germination, S. lycopersicum, B. rapa var. japonica, and V. locusta were more sensitive to 1 mM leaf juglone, and L. sativa was more sensitive to 1 mM control juglone. This suggests that this walnut leaf extract contains specific phenolic substance(s) that can stimulate seed germination in some species and inhibit it in others. Seedling length was more sensitive to 1 mM leaf juglone than 1 mM control juglone, with selective strong inhibition of root length versus shoot length by 1 mM control juglone. Juglone also had significant effects on the secondary metabolism of L. sativa, in particular for seedlings treated with 100 μM control juglone, with marked decreases in all secondary metabolites studied. Flavonols constituted the majority of these metabolites in L. culinaris, which showed the least sensitivity to both control juglone and leaf juglone treatments. Thirty compounds were identified and quantified in S. lycopersicum, L. culinaris, and L. sativa, some for the first time in these plants, and all for the first time in the seedlings of these crop vegetables.

Soil salinization has become one of the major problems that threaten the ecological environment. The aim of this study is to explore the mechanism of salt tolerance of hybrid walnuts (Juglans major × Juglans regia) under long-term salt stress through the dynamic changes of growth, physiological and biochemical characteristics, and anatomical structure. Our findings indicate that (1) salt stress inhibited seedling height and ground diameter increase, and (2) with increasing salt concentration, relative water content (RWC) decreased, and proline (Pro) and soluble sugar (SS) content increased. The Pro content reached a maximum of 549.64 μg/g on the 42nd day. The increase in superoxide dismutase (SOD) activity (46.80–117.16%), ascorbate peroxidase (APX) activity, total flavonoid content (TFC), and total phenol content (TPC) under salt stress reduced the accumulation of malondialdehyde (MDA). (3) Increasing salt concentration led to increases and subsequent decreases in the thickness of palisade tissues, spongy tissues, leaves, and leaf vascular bundle diameter. Upper and lower skin thickness, root periderm thickness, root diameter, root cortex thickness, and root vascular bundle diameter showed different patterns of change at varying stress concentrations and durations. Overall, the study concluded that salt stress enhanced the antireactive oxygen system, increased levels of osmotic regulators, and low salt concentrations promoted leaf and root anatomy, but that under long-term exposure to high salt levels, leaf anatomy was severely damaged. For the first time, this study combined the anatomical structure of the vegetative organ of hybrid walnut with physiology and biochemistry, which is of great significance for addressing the challenge of walnut salt stress and expanding the planting area.

The present study was designed to identify and quantify the major phenolic compounds in different Juglans regia L. (common walnut) tissues (leaves, petioles, bark, roots, buds), to define the compositions and contents of phenolic compounds between these tissues. A total of 91 individual phenolic compounds were identified and quantified, which comprised 8 hydroxycinnamic acids, 28 hydroxybenzoic acids, 11 flavanols, 20 flavonols, 22 napthoquinones, and 2 coumarins. Naphthoquinones were the major phenolic group in leaves, petioles, bark, and buds, as >60% of those identified, while hydroxybenzoic acids were the major phenolic group in side roots, as ~50% of those identified. The highest content of phenolic compounds was in the J. regia main root, followed by side roots and buds, leaves, and 1-year-old bark; the lowest content was in petioles and 2-year-old bark. Leaves, roots, and buds of J. regia represent a valuable source of these agro-residues.

Girdling, based on the accumulation of photosynthetic products above the girdling zone, is a common technique applied to tree species to increase the yield and fruit quality. The aim of this study was to investigate the girdling effects on photosynthesis and soluble sugars (Sols) of leaves in fruiting shoots and, for the first time, on quality variables of ‘Franquette’ walnuts harvested at two harvests, early and late, 43 and 84 d after treatment, respectively. Girdling was conducted on a part of four-year old branches at the onset of kernel growth. At late harvest, coinciding with commercial harvest, girdling advanced the mature fruit percentage, kernel weight, and oil content, whereas decreased kernel moisture and slightly affected the color brightness, although kernels remained with an extra light color. Advanced maturation increased linoleic acid and polyunsaturated fatty acid (PUFA) fraction in oil, whereas it decreased palmitic acid and the saturated fatty acid (SFA) fraction in oil, kernel total antioxidants, and Sols (sucrose, glucose, fructose) in kernels and leaves and leaf photosynthesis (Pn), whereas girdling had no effect on these variables. Oil rancidity remained stable throughout the experiment. Development of callus was observed on tree wounds 84 d after treatment. Conclusively, girdling enhanced the fruit maturation, resulting in higher uniformity of maturity and increased oil yield with no quality deterioration or apparent tree damage.

The present study was carried out to investigate the yield, quality, and metabolomic responses of four different vegetable crops to treatments with pure juglone standard and walnut (Juglans regia L.) leaf extract at soil concentrations found in walnut orchards. A total of 60 phenolic compounds were identified and quantified, some for the first time in these crop vegetables. Beta vulgaris L. and Lactuca sativa L. were less susceptible to juglone. For crop quality, B. vulgaris showed the least effects of the different treatments. Both Brassica rapa L. var. japonica and Valerianella locusta Laterr. showed lower yields, even at the lower juglone concentration, and reduced quality, so their cultivation in juglone-containing soils should be avoided. This study also investigated leaf quality at different ages and the quality and yield of these crop vegetables grown under the influence of allelochemicals, to determine the influence of allelochemicals on metabolomics and, thus, on the uptake of phenolic compounds considered to be beneficial to human health.

Growing concern for economic and environmental issues emphasizes the potential value of intercropping systems in temperate regions. However, the selection of relevant tree species to be associated with crops has been little documented. The growth and the nitrogen nutrition of two economically valuable species, wild cherry (Prunus avium L.) and hybrid walnut (Juglans nigra L.×Juglans regia L.), were compared over six years after plantation. These two species were associated with non-irrigated cereal crops in the agroforestry treatment or grown separately (weeded control and fallow). Intercropping increased diameter growth as soon as year 2 in the two species. Leaf biomass assessment using allometric models showed an earlier and greater leaf biomass increase in hybrid walnut than in wild cherry tree. After six years, the relative growth increase of the agroforestry trees with respect to the control trees varied with the parameter considered (diameter at breast height from +26 to +65%, leaf biomass from +54 to +142%) and with the tree species (higher relative growth for hybrid walnut trees). The beneficial effect on tree growth can be accounted for in terms of enhanced nitrogen nutrition. The tree–crop association in intercropping systems, which improves tree growth, might thus allow the planting of more demanding trees on soils of lower fertility

The organogenetic cycle of shoots on main branches of 4‐year‐old Juglans regia trees was studied. Mono‐ and bicyclic floriferous and vegetative annual shoots were analysed. Five parent annual shoot types were sampled between October 1992 and August 1993. Organogenesis of summer growth units was monitored between 16 Jun. and 3 Aug. 1993. Variations over time in the number of nodes, cataphylls and embryonic green leaves of terminal buds were studied. The number of nodes of parent shoot buds was compared with the number of nodes of shoots derived from parent shoot buds. The spring growth units of mono‐ and bicyclic shoots consist exclusively of preformed leaves which were differentiated, respectively, during the spring flush of growth (mid‐April until mid‐May) or the summer flush of growth (mid‐June until early August) in the previous growing season. Thus, winter buds may consist of flower and leaf primordia differentiated in two different periods during annual shoot extension. The summer growth units of bicyclic shoots consist of preformed leaves that were differentiated in spring buds during the spring flush of growth in the current growing season. Bud morphology is compared between spring and summer shoots.

The length and basal diameter of all lateral and terminal buds of vegetative annual shoots of 7-year-oldJuglans regia trees were measured. All buds were dissected and numbers of cataphylls, embryonic leaves and leaf primordia were recorded. Each axillary bud was ranked according to the position of its associated leaf from the apex to the base of its parent shoot. Bud size and content were analysed in relation to bud position and were compared with the size and number of leaves of shoots in equivalent positions which extended during the following growing season. Length and basal diameter of axillary buds varied according to their position on the parent shoot. Terminal buds contained more embryonic leaves than any axillary bud. The number of leaves was smaller for apical and basal axillary buds than for buds in intermediate positions on the parent shoot only. All new extended shoots were entirely preformed in the buds that gave rise to them. Lateral shoots were formed in the median part of the parent shoot. These lateral shoots derived from buds which were larger than both apical and basal ones.